Subject: Re: com rumblings...
To: John F. Woods <>
From: Iain Hibbert <>
List: tech-kern
Date: 06/16/2006 22:04:18
On Thu, 15 Jun 2006, John F. Woods wrote:

> I see
> 	com1: 1 silo overflow, 0 ibuf floods
> from time to time on a full-time modem link with a 350MHz P4.  The serial
> port is a 16550A (or emulation thereof) with a putatively "working fifo",
> according to dmesg.
> This is probably something simply sitting on the interrupt mask for way
> too long, and the com(4) driver is thus not at fault.  But it would be nice
> to figure out what is blocking interrupts for tens of milliseconds or however
> long this works out to be...

Well, if anybody is so inclined to try to do that, I believe this dates
from between 1.6 and 1.6.1

I posted a message to port-i386 in May 2003 (Subject: "silo overflows")
describing these symptoms and there was some comment (Hi Greg) but no

prior to whatever changed, my 486DX/50 with 8520 uart handled 19200 just
fine, even under load..